1. Field of the Invention
The present invention relates to an image pickup apparatus which performs image restoration processing for a shot image.
2. Description of the Related Art
Recently, a high-quality shot image is desired along with a high-definition of a display device. However, the quality of the shot image is deteriorated due to an influence of aberration or diffraction by an optical system. On the other hand, a method of improving a quality of a shot image by applying an inverse filter for the deterioration such as a Wiener filter to the shot image (an image correcting method) is proposed. However, in the image correcting method of using the inverse filter, a frequency component in which an MTF (Modulation Transfer Function) is small cannot be restored.
International Publication No. WO2007/074649 discloses a method of reducing the decrease of the MTF in a depth direction by inserting a phase modulation element into an optical system. Japanese Patent No. 4872862 discloses a method of restoring a lost frequency component by a super-resolution through study to remove a blurring caused by a hand movement (a hand shake) or defocusing from an image.
However, the method disclosed in International Publication No. WO2007/074649 is a method of reducing the decrease of the MTF in a defocused region, which cannot obtain its effect in a focus position. In other words, the purpose of International Publication No. WO2007/074649 is only to enlarge the depth of field, and therefore it cannot restore a frequency component in which the MTF is small due to the influence of the aberration or the diffraction. In addition, since it is necessary to have a special optical system configured by inserting the phase modulation element at the time of shooting an image, a shot image cannot be corrected. On the other hand, since the purpose of the method disclosed in Japanese Patent No. 4872862 is to remove the blurring caused by the hand movement (the hand shake) or the defocusing, similarly it cannot restore a frequency component in which the MTF is small due to the influence of the aberration or the diffraction.